CHEMISTRY COMMUNITY

Timothy Kim 1B

I had a similar question. but I noticed that when using this form of the first-order rate law, the solutions were consistent with leaving out the volume.

Timothy Kim 1B

Use the half-life equation for the second-order reaction. then substitute A for the fraction of A naught.

Timothy Kim 1B

would the unique rate for the formation of NOBr have a coefficient of 2?

Timothy Kim 1B

just to the extent that he covered during lecture.

Timothy Kim 1B

The slow step determines the rate of the reaction so that is where you get your rate law from.

Timothy Kim 1B

raising temp will increase the rate constant and the speed of the reaction.

Timothy Kim 1B

It all comes down to using two sets of the Arrehenius equation and creating a ratio out of the two.

Timothy Kim 1B

I believe it decreases the activation energy which will in turn increase the rate constant and rate of the reaction.

Timothy Kim 1B

Yes, half-life works for that fraction.

Timothy Kim 1B

Reaction order would be the exponent for the concentration in the rate law.

Timothy Kim 1B

Since it is a fraction, the value would appear flipped when it is used in the second-order reaction. take a look at the respective equations and you will see that the values correspond to each other.

Timothy Kim 1B

Why should k increase more than the k of the reverse reaction?

Timothy Kim 1B

what should be the final answer?

Timothy Kim 1B

yes due to the ratio.

Timothy Kim 1B

Its important to note that everything in the reaction should have the same unique rate.

Timothy Kim 1B

I believe that in order to produce B, A has to be used up. Therefore, B uses x amount A so we subtract A initial minus x.

Timothy Kim 1B

The 2 is there due to the ratio of the coefficients between the reactants and the products.

Timothy Kim 1B

Generally, a higher activation energy will require more energy input, which will lead to a relatively slower reaction.

Timothy Kim 1B

Aren't the unique average rates positive for both products and reactants?

Timothy Kim 1B

don't you also have to check with the half reaction of iodine in this case too?

Timothy Kim 1B

For the anode, there is no water. Where did the water come from based on the solution manual?

Timothy Kim 1B

When given this following pair, I3-/I-, the half-reaction is I3- +2 e- --> 3 I-.

How did this half-reaction come about? I was unsure about how to find the number of electrons in this case when the charge is both negative one on each side.

Timothy Kim 1B

When calculating these problems, how do we figure out n, the number of moles of electrons?

Timothy Kim 1B

I believe you should understand that this equation comes from the two Gibbs free energy equations that we have learned.

Timothy Kim 1B

Can you explain the differing Cv values for each of the gases in the solution manual corrections?

Timothy Kim 1B

I believe this problem's solution is on the solution manual errors. A and C should have the same amount of disorder.

Timothy Kim 1B

Would a spontaneous reaction (negative free energy) be more stable?

Timothy Kim 1B

It allows us to calculate K at a different temperature if the standard enthalpy of reaction is known.

Timothy Kim 1B

In edition to a reversible reaction being more efficient (more useful work done), a reversible has a constant Temperature and Volume and Pressure are inversely related.

An irreversible pathway has a changing temperature and work is done against a constant external pressure.

Timothy Kim 1B

You would find the entropy change for both change in pressure and volume and add the net change for this reaction.

Timothy Kim 1B

Entropy can still increase in these instances.
For instance, even when the entropy of an anabolic reaction decreases, there is still heat released to the surroundings, thus increasing the entropy change.

Timothy Kim 1B

If there are two states for one particle, degeneracy is 2^1.
For N particles in one of two states, degeneracy (w) = 2^N

Timothy Kim 1B

In the first question, we use the first formula because it is asking for entropy at a constant pressure. when you derive the equation, it comes out as that. For the second problem, the conditions are different because it is isothermal. Thus, you end up using a different equation that keeps into acco...

Timothy Kim 1B

It depends on the question, whether it is asking entropy per mole or not.

Timothy Kim 1B

Hi RenuChepuru1L, The heat of the reaction is equal to the negative heat of the calorimeter because the calorimeter is gaining heat from the reaction. Hence to calculate heat gained by the calorimeter, we use C(delta T). The question asks for the internal energy change for the reaction of 1.00 mol ...

Timothy Kim 1B

I had the same question. But I think as long as we are consistent throughout the problem, either options work.

Timothy Kim 1B

In 8.67 b, where do we find that the value to atomize one mol of C equals 717 kJ/mol?

Timothy Kim 1B

For heat capacity/specific heat, do we use kJ or J? Or does it really matter, as long as we stay consistent?

Timothy Kim 1B

An extensive property is dependent on the amount of a substance.
We get an intensive property when we divide heat capacity by the amount of substance present.
We use extensive and intensive properties when dealing with specific heat capacities.

Timothy Kim 1B

If you look at the heating graph, the enthalpy of vaporization is a longer line than the enthalpy of fusion. This shows that there is a greater amount of heat given off by the steam during its phase change.

Timothy Kim 1B

Standard reaction enthalpy is the reaction enthalpy when all R and P are in their standard state at 1 ATM.
Standard enthalpy of formation is the standard reaction enthalpy for the formation of one mole of a substance from its elements in their most stable form.

Timothy Kim 1B

for Week 9, problem 6c, why does expansion favor products?

Timothy Kim 1B

So does the Equilibrium constant still equal 10^-14 even if the temperature does not equal 25 degrees?

Timothy Kim 1B

How do you know if a metal oxide produces a strong base?
How do you know if a non-metal oxide produces either a strong or weak base?

Timothy Kim 1B

a. Is NH3 a Lewis base because it wants to donate the lone pair?
b. Is BF3 a Lewis acid because it wants to accept an electron pair to form a full octet?
c. Why does Ag+ (a Lewis acid) want to gain an electron pair?

Timothy Kim 1B

For part c, why is there no proton transferred when CH3COOH gains a hydrogen to become CH3CONH2?

Timothy Kim 1B

Polydentates have multiple bonding sites. CO3^2 has multiple spots because the lone pairs of its oxygen allows for different bonding spots.

Timothy Kim 1B

If the atoms have a formal charge of 0, it will not want to bind with anything, correct?

Timothy Kim 1B

This problem says to write out the formula of sodium bisoxalato(diaqua)ferrate(III).

How come oxalato in the answer is written after aqua?
It goes (OH2)2 (C2O4)?
When they tell us to write out the formula alphabetically, are we using the name or the symbols for alphabetical order?

Timothy Kim 1B

A double bond needs both a pi bond and sigma bond. When two atoms are bound by more than one covalent bond, the additional orbitals overlap side by side to form pi bonds.

Timothy Kim 1B

It's based on the structure of the bonds. When we look at how the pi bonds are connected, there is no room for rotation without the bonds disconnecting. But when we look at sigma bonds, their cylindrical interaction allows rotation.

Timothy Kim 1B

Lone pairs are the reasons for the bond angles being closer together. We learned in class that the lone-lone pair repulsion strength is the greatest, followed by the lone-bonding pairs. We know that bonding pairs want to be as far apart as possible. Thus, the explanation for the bond angles being cl...

Timothy Kim 1B

With VSEPR Models, molecules can have the same amount of electron densities. The difference in these molecules can lie in the angles between the bonds. For instance, trigonal pyramidals have different bond angles. Sulfite have O-S-O bond angles of 106 degrees while NH3 has H-N-H bond angles that are...

Timothy Kim 1B

With these two charges, find the lowest common factor between the two. Use this lowest common factor as the subscript for the opposite charges.

Timothy Kim 1B

For problems with molar mass, should we stick with grams always even if the SI unit is kilograms?

Timothy Kim 1B

Why does Oxygen go against the trend of having an increasing ionization energy to the right of the periodic table?

Timothy Kim 1B

Why does the energy of a electron increase from a 1s to a 2p orbital?

Timothy Kim 1B

Under certain circumstances is the 3d state lower in energy.
Once the 4s state is occupied and the electron enters the 3d state, then the 3d state is lower in energy than 4s. If the electron hasn't reached 3d yet, then 4s is written first.

Timothy Kim 1B

I think after the 4s state/orbital is occupied and the electron enters the 3d state, then the 3d state is lower in energy than 4s.

Timothy Kim 1B

Hi, I have two questions: 1. when we are finding the change in energy using the equations, are we finding the change in energy of only the electron? Will the change in energy be either positive or negative based on if the electron is absorbing or emitting? 2. When an electron emits a photon, will th...

Timothy Kim 1B

when finding the molar mass in the periodic table, how many sig figs do we use?

Timothy Kim 1B

Hi, when there are numerous instances in a problem when multiplication/division is needed, can we just find the final answer and do the sig fig in the end after all the multiplication? Also, is a problem with both addition and multiplication different because you have to recount the sig figs after y...

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